Composition for carroting fur and the like



Patented Jan. 8, 1952 TNT OFFICE COMPOSITION FOR GARROTINGFUR AND THELIKE I .B cm Tu k ni a a g and R m n 'lj mnerthltwtcwn, 3011111.,assignors to The HJ- 1 9 firmwar- Danburir, 1

No Drawing, Application December 23, 19.49,

,Sei'ialNo.134.860

.5 Glaims. (o1. s-,1 1 2;

Our invention relates to the treatment of fur and similar animal fibersto improve the felting qualities, otherwise shown as car-roting, andmore particularly to a composition of matter adapted to be employed insuch treatment.

To produce a material such as felt from fur and the like, it is firstnecessary to treat the fur to promote ease and rapidity of felting, andto acquire a high strength product. A preliminary chemical treatment,known as carroting, is-generally used, and it involves applying arelatively strong oxidizing and/or hydrolyz ing aqueous solution to thefur before it is sheared from the skin. The solution may be applied byany suitable means, as by brushing, and the pelts are either air-driedor 'ovensdried before shearing. The. fur .is then graded, blended, and,by a process of treatment with hot water and pressure applications, isformed into a felt whereby fibers become tightly interlocked andcompactly associated with one another.

The chemical reagents have the faculty of rendering this process of.felting more thorough and efficient, the mechanics of which have neverbeen explained satisfactorily. Nevertheless, perhaps the most successfulcarrot is an acid solu tion of a mercury salt, but being toxic it maynot be used because of its harm to the workmen. Consequently, manysubstitutes have been developed, and these generally are strongsolutions 5 of oxidizing and hydrolyzing reagents such as mineral acids,organic'acids, salts of these acids. peroxides, and the like. Acarroting solution by its very nature damages the fur, and so theproblem in selecting any composition ,for. this purpose is to providesufiici'ent treatment foisuccessful felting without at the same timedcstroying the strength of the fibers. Accordingly, a common difiicultyarises from the use of these mercury carrot substitutes because theyordinarily must be relatively strong to render the fur feltable, withthe result that fibers are inordi-' nately damaged. Indeed thesesubstitutes have a high specific gravity, normally above 6 Baum, andgenerally about 8 Baum.

It is accordingly among the objects of our in vention to provide acarrotlng solution which renders fur felta ble without deleteriouslyaltering the strength and wearing qualities of the final product. Afurther obi ct is to provide a successful and practical carrotingsolution with a low specific gravity, for example, in the range of 3 5"-Baum. Anoth'er ob ect is to use a'carrot-ing solu- 'tion composed 'ofinexpensive reagents whereevery possible, and to employ only smallpercentages of expensive ingredients so that theLcos-t oi carroting ismaintained within commercially ac: ceptable limits. A still furtherobject is to provide a carroting solutionwhichis not toxic underordinary conditions of its use.

Various changes in and departures from the embodiment of our carrotingcomposition may made as the same is -hereinaf;ter exemplified, allwithin the scope of our generic invention, it being understood that thematter ,set iorth. is submitted as illustrative and not in a limitingsense.

Our new and improved composition is aqueous solution 9. reagents whichare well known for their oxidizing and/or hydroly zing characteristics,but which are combined in such proportions and with certain otheringredients that a far weaker solution than hitherto-thought possiblecan be used to carrot fur for successful ltin solution does not undulydamage the fur so that strong, high quality felt is produced.

The preferred embodiment of our carroting solution contains .a smallpercentage of one -.,or more strong or moderately strong acids, ssuchxashydrochloric and nitric, together with .an oxis dizing agent such ashydrogen peroxide, and a small amount of ethyl alcohol, to produce asolution with aspecific gravity in the order of 3-'5 Baum. Such weaksolutions are incapable of carroting the fur within practical limits,but we have discovered that the addition of a small amount of eitherphosphotungstic acid or phosphomolybdic acid renders them highlysatisfactory for this purpose.

This preferred solution contains nitric acid in the order of 1-3%'together with 04.5% hydrochloric acid, though nitric acid may he usedalone with equivalent results. These proportions are computed aspercentages of HNQs and H01, respectively. in the entire weight ofliquid. In addition to the acid, a small. amount .of strong oxidizingagent, such as. 343% by weight oi hydrogen peroxideis used (computed. asH209, together with 0.3 1% by weight of ethyl alcohol (computed asCal-IsOI-I). The specific grav ity of the final mixture is about '3Baum. Carroting with this solution is not successful, but when -0.1-0.4% by 'weight of either phosphotungstic acid or phosphomolybdic acidor a combination of the two is added, a high strength, good quality feltcan be produced. The specific ravity of the-final tsolutionispreferablywithin Being relatively week. however, the

the range'of 3-5 Baum. and consequently little damage to the fur isencountered as with other known solutions ranging from 6-8 Baum andupwards;

Considering the infinitesimal amounts of the phospho'tun'gstic orphosphomolybdic acids which are employed, his most probable thata-catalytic action is encountered, whereby the reagents are utilizedmore efficiently. The weak solution in itself is not satisfactory andtherefore it would seem that such a small proportion of the phos;--photungstic and phosphomolybdic acids would desire to be restricted inour invention to any particular theory, it being sufiicient that the"result herein described is accomplished.

Several tests have been conducted to determine composition limits andsubstitutes for our preferred carroting solution. Considering the acids,those which are strong or moderately strong are the most useful;andtheir content should be kept quite low, commensurate with goodresults, and indeed it shouldnever be necessary to use over 4.5% byweight. Highlysatisfactory carrots are obtained by the use of thecombination of nitric acid and hydrochloric acid, or of nitric acidalone; however hydrochloric acid by itself appears inferior.

The strongoxidizing agent, hydrogen peroxide, supplements the action ofthe acid in treating the animal fibers,'but its concentration ismaintained within the limits of 35% to avoid undue damage which weakensthe final felt. I I

' A' small amount of organic solvent, such as ethyl alcohol, isbeneficial in causing the fibers to wet more readily, and its cleansingproperties are generally thought to cause more uniformity of treatment.V v

Since the carroting reaction by its very nature causes damage to furfibers, the primary object in developing any satisfactory compositionfor this purpose is to balance the adverse factors so that the bestcombination of quality and strength of felt is obtained. OfttiineS agood quality felt, as judged by the feel, may be produced from furwhichis rather severely damaged, but the final product will have poorwearing properties and will prove to be weak when judged by certainphysical tests such as tensile strength and flexing valuedeterminations. Conversely, when damage is avoided it is impossible toobtain a good, strong, tight felt. Either the felting rate is so slowthat an appreciable quantity of fur is .lost while felting, or feltingstops before final size is reached, after which further work merelyincreases the size of the hat body.,

The limits of (LL-0.4% for phosphotungstic or phosphomolybdic acids arecritical in providing the optimum combination of strong, good qualityfelt, 7 These were determined by preparing a series of basic carrotingsolutions containing 1.54% HNQ3, 0.' 73% HCl, 0.4 C2H5OH, 3.3% H202 andphosphgtungstic acid varying in amounts from to 1.6%. These varioussolutions were then used to carrot rabbit fur, and felt hats were madeby usual commercial practice. I The flexing test is perhaps the mostsignificant physical test for evaluating damageto fur felt, whetherresulting from carroting'or subsequent manufacturing processes such'as'dyein'g. A flexing' machine "is commercially-available for this 4test, and its use on fur felt hats is well known in the art. In thistest a sample of felt one-half inch wide and six inches long is held ina flexing machine under tension of two and one-half pounds and issubjected to repeated-bendings at 'the rate of 110 flexes perfminuteuntil it breaks.

The flex value is the average number'of flexes required to break eightsamples cut from different portions of the hat so that all sectionsthereof ma e tested-;.

Aifelt made from fur carroted with the basic solution withoutany.phosphotungstic acid has a highflex value because the solution is weakand-doeslit'tle damage. As mentioned above, this basic solutioncomprises 1.54% 'HNOa, 0.73%

H01, 0.4% C2H5QH and 3.3% H202, balance water.

' However, the felt is loose and soft as judged by its feeL-and the timeand number of operations relower-as the amount ofphosphotungstic acid inthe carroting solution is increased, and when 0.4% is exceeded thequality and felting rates are erratic and the felts are of such poorstrength I as not to be useful commercially. Consequent- '1y,.th epracticalrange is between 0.1414 phos photungstic acid in the'carrotingsolution hav ing a specific gravity of only 3-5 Baum. Phosphomolybdicacid may be substituted in like amounts to obtain equivalent results.

The phosphotungstic acid employed in the above-tests hasthe formulaP2O5.24WO3.44H2O. and the phosphomolybdic acid has the formula20MoOa.2IrhPO4.48I-I2O. v

The cost of these acids is very high and fo commercial use. it isusually advisable to limit its concentration to about 0.2%, since theresults appear equally satisfactory throughout the recommended range. VQ

As many possible embodiments may be made of the above invention and asmany changes might be madein the composition above set forth, it is tobe understood that all matter hereinbefore set forth is tobe interpretedas illustrative and not in a limiting sense What is'claimed is:

1. As a composition of matter for the carroting of fur or the like, anaqueous carroting solution containing. a non-hydrolyzing oxidizingagent, a volatile hydrolyzing acid, and an acid of the groupconsistingrof phosphotungsticacid and phosphomolybdic .acid as acatalyst, said solution having the proportions of 1.0-4.5% by weightsaid hydrolyzing acid, 375% by weight said oxidizing agent, and.0.l-.0.4%.by weight of said latter acid or acids, l i

v2. An aqueouscarroting solution for treating fur. and the likecontaining3-5.% byweight hydrogen peroxide, 1-3% by weight nitric acid,and as a catalyst 0.l-0.l% -by weight phosphotungstic acid, the specific,gravity of said solution being between 3-5" Baum.

3. An aqueous-carroting solution for treating fur and the likecontaining3-5% by weight hydrogen peroxide, 1-3% by Weight nitric acid,- and asacatalyst '0.1-0-.4% by 'weightphosphomolybdic acidpthe specific gravityof said solution being between 3-5" Baum.

4. Anaqueous vcarroti-ng solution fortreating fur and theiikecontaining1-3 by weight nitric acid,- hydrochloric 'acid'-not'-to exceed 1.5% byweight; 35%- by: weight-hydrogen peroxide; as a ata yst- 0,141 ab!weieht-.-p osp tunsst c acid, and 0.3-1.0% by weight ethyl alcohol, thespecific gravity of said solution being between 3-5" Baum.

5. An aqueous carroting solution for treating fur and the like,containing 3-5% by weight hydrogen peroxide, 1-3% by weight nitric acid,0.3-1 by Weight ethyl alcohol, and as a catalyst 0.1-0.4% by weightphosphotungstic acid, the specific gravity of said solution beingbetween 3-5 Baum.

The following references are of record in the file of this patent:

6 UNITED STATES PATENTS Number Name Date 1,710,565 Bohm Apr. 23, 19292,048,645 Fabian July 21, 1936 2,087,854 Fabian 1 July 20, 19372,169,997 Fabian Aug. 22, 1939 2,181,884 Giuliano Dec. 5, 1939 2,242,668Dolid May 20, 1941 2,330,813 Donner Oct. 5, 1943 2,411,725 Hodshon eta1. Nov. 26, 1946 FOREIGN PATENTS Number Countiy Date 323,944 GreatBritain Jan. 16, 1930 441,619 Canada 1947 (Through J Am. Leather Chem.Assn., Nov. 1947.

page 588) 803,872 France Oct. 10, 1936

1. AS A COMPOSITION OF MATTER FOR THE CARROTING OF FUR OR THE LIKE, ANAQUEOUS CARROTING SOLUTION CONTAINING A NON-HYDROLYZING OXIDIZING AGENT,A VOLATILE HYDROLYZING ACID, AND AN ACID OF THE GROUP CONSISTING OFPHOSPHOTUNGSTIC ACID AND PHOSPHOMOLYBDIC ACID AS A CATALYST, SAIDSOLUTION HAVING THE PROPORTIONS OF 1.0-4.5% BY WEIGHTT SAID HYDROLYZINGACID, 3-5% BY WEIGHT SAID OXIDIZING AGENT, AND 0.1-4% BY WIEGHT OF SAIDLATTER ACID OR ACIDS.